Typically in wireless messaging systems, link systems connect the control point(s), where transmission service requests or information enters the system, to the transmission sites, where the wireless service is actually delivered to the customer unit. Transmission service requests represent requests to deliver messages (data or voice) to particular wireless receivers via a network of transmitter sites. Modern wireless messaging systems usually provide wireless transmission services over large geographic areas, such as nationwide service, i.e., a service which provides coverage for the vast majority of the populated areas within a country. The wide geographic scope of these systems often requires the use of data communication systems, such as a satellite or other broadcast link systems, between the control points and the transmission sites.
Generally, wide area messaging systems provide total coverage as a sum of smaller, discrete systems, each discrete system having one or more transmission sites providing coverage for a zone or region. Nationwide service, therefore, may represent the sum of a number of zones or regions, such as Metropolitan Trading Area (MTAs) or states. This piecewise construction of wide area messaging systems impacts link system requirements. As each discrete system of a zone operates essentially as a stand-a-lone system, the typical wide area messaging system must provide for the linking and controlling of a number of discrete transmission systems. In general, for a single zone, customer transmission request information is batched (or grouped) at the control points and then passed over a satellite or other broadcast link systems to transmission sites for subsequent transmission. When customer transmission requests result in transmissions over multiple zones, the same customer transmission request information is multiply batched (one for each zone) and multiply carried as batched information in aggregate over the link system(s). Assuming an efficient transmission control system, the majority of the link bandwidth required for any given discrete zone of a system is the customer transmission request information. For example, if the customer transmission request information is targeted for delivery over two zones, then the customer information is sent, in aggregate, twice per request over the link system, once for each zone. If the customer information were targeted for three zones, then it would be sent three times per request, and so on. The batching of information at the control point equipment to each zone greatly increases link system bandwidth requirements, and thus reduces system efficiency. Moreover, when the link systems are satellite-based, this is very costly as satellite bandwidth has a relatively high cost per bit of broadcast data.
The batching at the control point equipment for a conventional link transmission control system is illustrated in FIGS. 1-4. FIG. 1 shows the typical basic link and control of transmissions to a single zone of transmitters. The system includes control point equipment 10, satellite uplink 11 and satellite 12, and the satellite downlinks 14 and transmitter controllers 15 of 1 to N transmitter sites 13. Transmission requests 18 are submitted to the control point equipment 10 which batches groups of transmission requests together, based on rules associated with a transmission protocol, into batched information. The control point equipment 10 forwards the batched information via the satellite uplink 11 and the satellite 12 to the transmitter sites 13 for ultimate transmission. At each of the transmitter sites 13a, 13b, 13c, . . . 13n, the satellite downlinks 14 receive the satellite broadcasts and forward the batched information to the transmitter controllers 15 which decode the batched information and control the transmitters 17 for actual transmission of the batched information via antenna 16. For simulcast transmissions from multiple transmitter sites which are geographically overlapping, the system operation synchronizes the time used for transmission from overlapping sites and the batching information includes a scheduled time of transmission for the batch.
The control point equipment 10 of FIG. 1 is shown in more detail in FIG. 2. The transmission requests 18 are accepted into a transmission request queue 20. A transmission scheduler 22 provides input to a batching process 21, which pulls transmission requests from the transmission request queue 20 and produces batches of transmission information which are 10 fed to a link protocol formatter 23 to prepare batch information for conveyance over the link system to the transmitter sites 13 (FIG. 1). The link formatted data is placed in the link transmission queue 24 pending actually transmission via the link system at its associated data rate.
Referring to FIG. 3, the typical link and control of transmissions to multiple zones 26 of transmitter sites is shown in which the control point equipment 10 controls transmissions to 1 to N zones 26a, 26b, 26c, . . . 26n. Each zone appears as a group of transmitter sites 13, as shown for example in FIG. 1, where each transmitter site has a satellite downlink 14, transmitter controller 15, transmitter 17, and antenna 16. The batching and transmission of information to multiple zones in the control point equipment 10 is shown in more detail in FIG. 4. For each zone 26 supported by the control point equipment 10, the control point equipment provides for a transmission queue 28, a batching process 29 and a transmission scheduler 30 (illustrated for the zones by blocks 31a, 31b, 31c, . . . 31n, respectively, in which only block 31a is shown in detail). Incoming transmission requests 18 are replicated in one or more transmission queues 28, depending on the service coverage to be provided. The transmissions for each zone are independently managed by the zone's associated transmission scheduler 30 and batching process 29, notwithstanding the shared use of the link protocol formatter 23, link transmission queue 24 and the associated link system. Transmission requests are duplicated for each zone's independent batching use, the batching processes produce batches with duplicates of transmission information and the duplicated information is link protocol formatted and sent over the link system. By duplicating transmitted information to each zone, the amount of information which must be transmitted in the link system is greatly increased, thus increasing the link system's bandwidth requirements and operating costs, and reducing system efficiency.